Tango Icon Library provides developers a set of professional high quality icons. They are in PNG ( Transparent background which can easily integrate into any web site) and SVG format ( Scalable which means you can increase the size of the icons without losing quality.

David Vignoni from Icon-King spent more than 1 year to create Nuvola version 1, the more professional, consistent and complete Nuvola theme ever released, it is one of the KDE themes. These icons look very cute and web 2.0 because of the glossy effect on each icon.

In many cases when we are developing a web site or web application, our traget market might not only be one country. We might provide different version for various people in different region or country. Here is a Flag Button Developement Kit created by Bartelme Design. We can create different flag buttons for different country easily.

Famfamfam offers us a set of wonderful and most pupular icons on the internet named “Silk” which contains over 700 16-by-16 pixel icons in strokably-soft PNG format. And all for a low low price of $0.00. You can’t say fairer than that.

Matt Ball is a student currently attending UCLA with a major in Computer Science and Engineering. He spent some of my spare time designed a set of good looking toolbar icons for us. These toolbar icons are very suitable for developing web applications and services.

IconBuffet is home to a tasty plethora of free icons. You’ll get one free delivery a month just for being a member at IconBuffet. Collect them, download them, trade them with your friends. You’ll earn badges as you send and receive sets, make friends, and invite others. You can more points by sending icons to friends and get badges. If you build up enough points, good things can start to happen. You’ll unlock extra features on the ’Buffet and might even earn some bonus tokens for more icons. You can use all icons you have got on any non-commercial or commercial websites.

Are you tired of using some small and ugly web 2.0 services icons? You should try the Web 2.0 Services Icons Pack which is made by Made by ilemoned and miniajax. They looks amazing and all in PSD and PNG formats, it is very easy to modified and blend it to your website.

Other than Tango Top Quality Vector Icons, there is another set of professional high quality icons – GNOME 2.18. GNOME 2.18 Icons are in PNG ( Transparent background which can easily integrate into any web site) and SVG format ( Scalable which means you can increase the size of the icons without losing quality. There are over 600 icons altogether. I think this is one of the best icon sets I have ever seen.

Does your web application have international appeal? Do you support multiple languages? Do you need a set of Flag Icons? Icon Drawer produced more then 220 flag icons representing countries and unions all over the world in PNG format. Sizes : 16×16, 24×24, 32×32, 48×48. They look so pretty.